The present invention relates to an awning, in particular an awning with a supporting arm, the cloth of which can be unwound from a tube or winding shaft driven by an electric motor and in which is provided a means for measuring the drive torque which supplies a variable representing the windforce acting on the awning cloth.
Such an awning is known from German Patent Application DE 44 07 342, the content of which is incorporated by reference. The tubular motor housing, mounted inside a winding tube, is fastened to a rigid bar by means of a plastic sleeve which allows some rotation of the motor housing around its support when a sufficient torque is applied to this housing. The housing is provided internally with two stops between which a bare is engaged which works by flexural stress and to which is fastened a strain gage supplying a voltage representing the torque. When high stresses are exerted on the deployed awning cloth by the wind, the motor housing is driven in rotation. Its stops exert flexural force on the bar carrying the strain gage connected to the device controlling the awning motor. As soon as the flexion of the detection bar reaches a particular threshold in one direction or the other, the winding of the awning is activated. The awning is stopped in intermediate positions by means of position sensors located outside.
It is known, moreover, from Patent Application EP 0,822,316, the content of which is incorporated by reference, to detect a predetermined angular displacement of a motor housing (restrained in terms of rotation by a spring) by means of optical sensors, in order to cut off the supply to the motor when the product driven by the motor reaches a limit stop at the end of its travel. This device therefore provides only discrete values which are determined by the position of the optical sensors. A new setting requires action on the motor in order to displace the optical sensors.
It is known, moreover, for example from Patent DE 40 09 373, the content of which is incorporated by reference, to measure the windforce by means of an anemometer. Not only does this solution make it necessary to mount an anemometer at a suitable point on the building, corresponding cabling or a wireless link by transmitter and receiver, but also the information obtained will usually not correspond to the stresses actually experienced by the awning cloth, the wind conditions being different in the region of the awning than in the region of the anemometer. Furthermore, an anemometer screw may seize up or be completely jammed due to ice.
It is desirable to permit intermediate positions of deployment of the awning cloth, so as not to eliminate completely the solar protection effect of the awning in the event of a wind of medium force which does not allow the cloth to be kept fully deployed, but allows a partially deployed cloth to withstand the stresses exerted by the wind.